[R] Resources for optimizing code

Janet Elise Rosenbaum jerosenb at fas.harvard.edu
Fri Nov 5 18:34:55 CET 2004

I want to eliminate certain observations in a large dataframe (21000x100).
I have written code which does this using a binary vector (0=delete obs,
1=keep), but it uses for loops, and so it's slow and in the extreme it 
causes R to hang for indefinite time periods.

I'm looking for one of two things:
1.  A document which discusses how to avoid for loops and situations in
which it's impossible to avoid for loops.


2.  A function which can do the above better than mine.  

My code is pasted below.

Thanks so much,


# asst is a binary vector of length= nrow(DATAFRAME).  
# 1= observations you want to keep.  0= observation to get rid of.

remove.xtra.f <-function(asst, DATAFRAME) {
	n<-sum(asst, na.rm=T)
	newdata<-matrix(nrow=n, ncol=ncol(DATAFRAME))
	for(i in 1:length(data)) {
		if (asst[i]==1) {
Janet Rosenbaum                                 jerosenb at fas.harvard.edu
PhD Candidate in Health Policy, Harvard GSAS
Harvard Injury Control Research Center, Harvard School of Public Health

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